1. Field of the Invention
The present invention relates to a shock-absorption steering apparatus.
2. Description of the Related Art
There have been provided shock-absorption steering apparatuses which absorb impact energy generated by a collision of a driver to a steering wheel due to collision inertia when a vehicle is collided with another vehicle or a building.
In such a shock-absorption steering apparatus, a steering column is generally supported to a vehicle body movably forward the vehicle body by an impact while collision energy is absorbed by limiting the displacement of the steering column during the movement.
However, if a driving condition, such as the driver, is changed, the load applied to the steering column is varied because of the difference in the driver's weight, for example, so that the impact energy may not be sufficiently absorbed. Hence, a shock-absorption steering apparatus that can control the amount of absorption according to the driving condition is proposed (Japanese Unexamined Patent Application Publication No. 2002-362381, FIG. 4). In this apparatus, the amount of energy absorption is adjustable by changing the rotational angle of a support pin so as to control the deformation of an energy absorption plate.
In the steering apparatus disclosed in the above publication, the rotational angle of the support pin is adjusted by a motor which, however, must have a large torque so as to overcome the reaction force generated when the energy absorption plate is deformed. Thus, the motor is increased in size and price. Furthermore, a mechanism for restricting the rotational angle of the support pin is additionally needed, resulting in the larger steering apparatus in size.